Add support for ECDSA to ssh-hostkey.nse.

Patch by Adam Števko. http://seclists.org/nmap-dev/2012/q4/181

CHANGELOG

@@ -1,5 +1,7 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [NSE] Added support for ECDSA keys to ssh-hostkey.nse. [Adam Števko]
+
 o [Nsock] Added new poll and kqueue engines. [Henri Doreau]
 
 o [Zenmap] Corrected some typos in the Japanese translation.

nselib/ssh2.lua

@@ -215,6 +215,15 @@ fetch_host_key = function( host, port, key_type )
     local n
     _, _, _, n = bin.unpack( ">aaa", public_host_key )
     bits = openssl.bignum_bin2bn( n ):num_bits()
+  elseif key_type == 'ecdsa-sha2-nistp256' then
+    algorithm = "ECDSA"
+    bits = "256"
+  elseif key_type == 'ecdsa-sha2-nistp384' then
+    algorithm = "ECDSA"
+    bits = "384"
+  elseif key_type == 'ecdsa-sha2-nistp521' then
+    algorithm = "ECDSA"
+    bits = "521"
   else
     stdnse.print_debug( "Unsupported key type: %s", key_type )
   end

scripts/ssh-hostkey.nse

@@ -136,6 +136,15 @@ local function portaction(host, port)
   key = ssh2.fetch_host_key( host, port, "ssh-rsa" )
   if key then table.insert( keys, key ) end
 
+  key = ssh2.fetch_host_key( host, port, "ecdsa-sha2-nistp256" )
+  if key then table.insert( keys, key ) end
+
+  key = ssh2.fetch_host_key( host, port, "ecdsa-sha2-nistp384" )
+  if key then table.insert( keys, key ) end
+
+  key = ssh2.fetch_host_key( host, port, "ecdsa-sha2-nistp521" )
+  if key then table.insert( keys, key ) end
+
   for _, key in ipairs( keys ) do
     add_key_to_registry( host, key )
     table.insert(output_tab, {